I don't know where to begin when I talk about Charles de Lint's books - they are wonderful! They are inspiring, evocative and well written, with memorable, very real characters, and they always evoke a sense of wonder. He writes novels and short stories, many of them set in his fictional town of Newford, Canada. One thing I love about his books is that they feature recurring characters. A main character from one book might have a bit part in another, or a supporting role, or star in a short story. Usually it doesn't even matter which order you read them in (and anyone who knows me knows what a stickler I am for reading books in order!). I would make an exception for this book, though.
Widdershins is a sequel to Onion Girl, so definitely read that one first. And I'd even start with some earlier books, just to get to know some of the other characters a bit better before you start with those, because with that extra background the books will have more meaning.
De Lint's books often (but not always) center on characters who are artists or musicians, and there are almost always elements of Native American religions and mythologies. Everything is connected, and the plot tends to spin off in unexpected directions. One of the central conficts in Widdershins is the enmity between the "first people" -- spirits from the Native American tradition, like crow people and decendents of Coyote and Raven -- and the creatures of Faerie, who immigrated to the New World hundreds of years earlier, but are forced to live in towns and cities, leaving the wild places for the native spirits.
Lizzie, a fiddler from a Celtic band, gets on the wrong side of a group of bogans bent on exacerbating the situation, and when she interferes, she becomes swept up in a chain of events as inexplicable to her as they are dangerous. Meanwhile Jilly, as recovered from her recent car accident as she's likely to get, is drawn into the situation when she and Lizzie mysteriously vanish from their beds in the night. Their disappearance exacerbates the brewing enmity, which quickly escalates to the brink of an outright war. Geordie (finally) recognizes his true feelings for Jilly, but she is in a place far from his reach, a place where she must confront the deepest fears from an abusive childhood in order to escape.
You know a book's good when 560 pages aren't enough!
Widdershins by Charles de Lint (Tor, 2006)